Why use rem instead of pixels?

Rem units scale relative to the root font size, which makes typography and spacing systems more flexible and better for accessibility.

What root size should I use?

Use the root font size defined in your project. Many projects use 16px, but not all do.

No. Designers and content teams use it too when documenting type scales and spacing systems.

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Switch between pixel-to-rem and rem-to-pixel conversion without needing a second calculator.

Use the root font size your project actually uses instead of assuming 16px.

Copy the converted result for CSS, design specs, or audits.

Choose a direction

Pick whether you are converting from pixels to rem or the other way around.

Set the root font size

Use the default 16px or enter the value your project is based on.

Read the result

The converted value updates immediately so you can paste it into code or documentation.

Calculate readable line-height values for headings, body copy, and long-form text.

Convert between pixels, points, picas, em, rem, inches, millimeters, and more.

Search a compact reference of common Tailwind utility classes and their CSS output.